package cn.edu.cauc.crab.ossimulate;import java.util.*;/** * <p>Title: OS simulate</p> * <p>Description: This is my home work.</p> * <p>Copyright: Copyleft (c) 2004</p> * <p>Company: CAUC</p> * @author Crab * @version 0.1 *//** * To simulate short process first process scheduling. * * @author Crab * @version 0.1 * @see cn.edu.cauc.crab.ossimulate.ProcessSchdule */public class SPFProcessSchedule extends ProcessSchedule {    /**     * extends from ProcessSchedule a List named PCBs     */    public SPFProcessSchedule() {        super();    }    /**     * extends from ProcessSchedule     * After addProcess() is calling,     * use to start scheduling.     */    public void start() {        int time = 0;//set the beging time        while (!PCBs.isEmpty()) {            PCB shortest = (PCB)PCBs.get(0);            Iterator p = PCBs.iterator();            while (p.hasNext()) {                PCB tempPCB = (PCB)p.next();                if (tempPCB.serveTime < shortest.serveTime                    && tempPCB.arriveTime <= time) {                    // the process must run >= arrive time                    shortest = tempPCB;                }            }            PCB pcb = shortest;            if (time >= pcb.arriveTime) {// the process must run >= arrive time                pcb.beginTime = time;                time += pcb.serveTime;                pcb.finishTime = time;                pcb.rollTime = pcb.finishTime - pcb.arriveTime;                // use tr ts to rise the precesion.                float tr = pcb.rollTime;                float ts = pcb.serveTime;                pcb.nullWorkRate =  tr / ts;                System.out.println("PID: " + pcb.pid                                   +" Arrive: " + pcb.arriveTime                                   + " Serve: " + pcb.serveTime                                   + " Begin: " + pcb.beginTime                                   + " Finish: " + pcb.finishTime                                   + " Roll: " + pcb.rollTime                                   + " nullWorkRate: " + pcb.nullWorkRate);                PCBs.remove(pcb);            } else {                time++;            }        }    }    public static void main(String[] args) {        ProcessSchedule pSch = new SPFProcessSchedule();        pSch.addProcess(new Process(4), 0);        pSch.addProcess(new Process(3), 1);        pSch.addProcess(new Process(5), 2);        pSch.addProcess(new Process(2), 3);        pSch.addProcess(new Process(4), 4);        pSch.start();    }}